Braking



March 22, 1938. '1". H. SCHOEPF ET AL.

BRAK I NG Filed March 16, 1937 3 Sheets-Sheet l INVENTORS THEODORE H.5CHOEPF BYDAVID MIRITCHIE, W fl W ATTORNEYS FIG. 2;

March 22, 1938. T. H. SCHOEPF ET AL. 2,111,812

BRAKING Filed March 16, 1957 3 Sheets-Sheet 2 INVENTORS THEODORE H. SCHOEPE nnvm m. RITCHIE BY MwM ATTORNEYS I March 22, 19.38."

T. H. SCHOEPF ET AL.

BRAKING File d March 16, 1957 3 Sheets-Sheet 3 QFHlZ.

low 34 INVENTORS THEODORE H. scum-r; DAVID m. mun/ 1 0&2 ATTORNEYS Paten t'ed Mar. 22,1938 2,111,812

UNITED STATES PATENT OFFICE "has; seminar in nati Traction Building Company, Cincinnati, Ohio, a corporation of Ohio Application March 16, 1937, Serial bio-131,206 6 Claims. (Cl- 303 -21) This invention relates to railway vehicles and section, of the electromagnetic valve device illusparticularly to the braking thereof. trated in Figure l;

It is an object of this invention to provlde for Figure 3 is an elevational view, partly in secrailway vehicles, braking means adapted to tion, of the axle speed responsive biasing rheostat achieve, when applied, the ultimate emciency of shown in Figure l; 5

deceleration, while preventing slippage or loss Figure 4 is a diagrammatic view illustrating of traction between the vehicle wheels and the the arrangement of the resistance elements of supporting tracks, and while achieving the utthe biasing rheostat illustrated in Figure 3, with most smoothness of operation. a respect to the armature thereof;

I It is a further object of this invention to pro- Figure 5 is a fragmentary diagrammatic view, 10 vide means responsive to the speed of a railway illustrating the application of the principles of .vehicle for controlling the intensity of wheel this invention, with track brakes having fluid brake application thereon. engine positioning means; and

It is a further object of this invention to pro- Figure 6 is a similar view illustrating the apvide means responsive to the speed of a moving plication of the principles of this invention with 15 railway vehicle to control the intensity of aptrack brakes applied through energization of a plication of the track brakes thereof. solenoid connected in the track brake shoe ener- It is a further object of this invention to progizing circuit.

vide means responsive to the speed of a moving The high speed of operation of new and modern 0 railway vehicle to simultaneously control the inmain line rail equipment requires, in the braktensity of application of the wheel and track ing of the vehicles, the application of the maxbrakes at a rate proportional .to the co-eiflclent imum allowable pressu to the wheel? y the of braking friction which is dependent upon the wheel brakes. It is desirable that the pressure speed of the moving vehicle. of application of the wheel brakes be controlled It is a further object of this invention to proand retained, at all times, at the maximum 25 vide such means whereby the downward force 4 limit 50 that the train Vehicle may be pp applied by the track brakes of a vehicle downin the shortest possible distance, with the utmost wardly upon the axles of the truck thereof will smoothness and the achievement of the maximum increase the traction between the moving vehicle braking effect and ultimate comfort to railway wheels and the supporting rails to reduce slippassengers. 30

page and loss of traction therebetween. Th determining f r n h appl ation of It is a further object of this invention to pro-' the wheel brakes is the adhesion or traction bevide such means which may be applied with tween thevehicle wheels and the supporting rails. facility and with minimum expense to railway All braking efl'ect exer d up n a r i w y-vehi le vehicles provided with conventional air brake by the wheel brakes is dep nd p the tree- '35 systems without the necessity for substantial tion between the wheels and the supporting rails. modification of the conventional braking sys-V Since the co-eflicient of friction between rubbing tems thereof: parts varies with the speed, the co-emclent of It is a further object of this invention to profriction between the brake shoes and the treads 40 vide, in such means, a common means assoof the vehicle wheels increases as the speed of i0 ciated with an axle of a railway vehicle to conthe vehicle decreases. I trol the intensity of wheel and track brake ap- The use of magnetic track brakes enables us plications at a' rate proportional to the speed of to materially increase the eiilciency of braking .the vehicle and proportional also to the co-efiland to bring to a stop, in the shortest possible 4:, cient' of braking friction which is proportional distance, a vehicle equipped both with wheel to the vehicle speed. brakes and with track brakes. The track brakes, These and other objects and advantages will in addition to applying a braking force which is appear from thefollowing description taken in additive to the braking force applied by the wheel connection withthe drawings. brakes, also exerts a downward force on the In the drawings: a wheels of the vehicle to which they are applied 50 Figure 1 is a diagrammatic view, showing the in order to breathe vehicle wheels against the application of the principles of our invention to rails and increase the adhesion or traction bethe automatic braking system and an axle of a tween the' wheels and the rails. railway vehiclei While the efficiency of wheel brakes is mate- ,55 Flgu1e'2 is an enlarged elevationai View, in rially impaired by unfavorabletrack conditions,

such as sleet, snow, ice and rain which materially decrease the traction of the wheels thereon, it is found that the track brakes are relatively unaifected by such unfavorable track conditions and-that they decrease the effect of such conditions on the wheel brakes by increasing the traction between the wheels and the track rails. In addition, the track brakes may besafely applied at all times at their maximum intensity, and it is our purpose, in controlling the intensity of application thereof, only to produce smoothness in stopping and comfort to the passengers of the Where, due to unfavorable track conditions,

the traction or adhesion between wheel and rail is reduced, upon application of the wheel brakes at too great intensity manually, by the operator,

or by other means, the wheels*will be locked and will slide upon the rail, thereby destroying all braking efliciency of the brakes. This undesirable condition most often arises during manual application of the wheel brakes, where the human.

element controls the rate of brake application. It is the principal object of this invention to 26 overcome this dangerous and undesirable occurrence by eliminating the human element as a controlling factorin brake application in order to secure the maximum possible. braking eiliciency at alltimes by controlling the intensity of wheel 30 brake application by tween rail and wheel regardless of track conditions in order to secure the maximum obtainable retardation with a given track condition and a given co-efllcient of braking friction or value of 35 traction or ,adhesion between wheel and rail. In the practice of our invention, the maximum retardation obtainable is secured for each given speed during application of the wheel brakes.

There is no iixed rate of retardation, and there 4 is no iixed te dependent upon the judgment ofthe huma operator. This invention, in operation, does not hinder or interfere with brake application, but governs the brake shoe More in proportion to the then existing 5 co-emcient'of traction or adhesion between wheel and rail forthespeed atwhich the train or vehicle is travfellng. 'Ihe fluid pressure in the brake cylinder is diminished or reduced as the speed is reduced and in proportion to the increase of co-' 0 eflicient of friction between the brake shoe and 1 Referring to the drawings in detail and'with reference particularly to Figure l, the conventional brake pipe I is connected by the pipe 2 to is the brake valve 3 which is provided with an inlet I, connected to 'any suitable source of fluid pressure, and the outlet i. The valve 3 may be manually operated to connect the pipe 2 to the pipe I in order to build up a pressure in the M brake pipe or to the outlet 6 to reduce the pressure in the brake pipe. The brake pipe I leprovided at each end with conventional angle cocks Ia and flexible hose connections lb.

Connected in the brake pipe I is the branch MpipeTOhavingconnectedtheretothepIpe'I which is also connected to the cutout cock, 6. The cutout cock 3 is connected by the pipe 3 to the centrifugal dirt collectorll- The dirt collector I3 is connected by the pipe II to the triple valve 10 I2. The triple valve is conventional and is con nected in known manner by the pipe I3 to the reservoir II and by the'pipe II to the electromagnetic valve device I, which electromagnetic valve device I 6 is connected to thefluid cylinder 7. II which operates the conventional wheel brakes.

traction or adhesion be-,

A T I3 is provided in the pipe It, to which is connected the pipe I9 which leads to the upper end of the cylinder of the pressure responsive switch 20. The pressure responsive switch 26 is in the form of an air engine having a cylinder 5 2I with a piston 22 slidable therein and adapted to be urged downwardly therein against pressure of the spring 23' by fluid pressure in the cylinder 2I above the piston 22.

Rigidly secured to the piston 22 is the stem 10 member 2I having a suitable switch plate 25 rigidly secured to the end thereof. The switch plate 25 of the pressure responsive switch is adapted to engage switch contacts 26 and 21 when the force of the spring 231s overbalanced 15 by pressure in the cylinder 2| above the piston 22. When the force exerted by the fluid pressure is less than the force of the spring 23, the switch plate 26 is disengaged from the switch contacts 26 and 21. 3

Contact 26 is connected by means of wire 3| with the coil 26 of the track brake shoe 33. The

' other terminal of the coil 26 is connected to the ground 26. Contact 21 is connected by wire 33 to the contactor bar Hill) which cooperates 26 with the contact plates IIlIa of the rotor III of rheostat 3I. The wire 32 is connected from brush I03 of rheostat 3I to the wire II whichis connected to one terminal of the reliei valve I2. The other terminals of the windings of 'the valve I6 and I2 are connected bythe cross wire I33 which cross wire I3 is connected by the wire II to the ground I6. The rheostat II is connected through tapped resistance "I and resistor I66 to the positive terminal of the source of power 35 35, the negative terminal of which is connected by the wire-36 to the ground 31.

When pressure is introduced into the cylinder 2I to urge the piston 22 downwardly therein and engage the switch plate 26 with the contacts 40 26 and 21, the brake coil energizing circuit is completed. The brake coil energizing circuit extends from the positive side of the source of power 36 through tapped resistance II and bar Nb of rheostat 3I, wire 33, contact 21, switch plate 25, contact 26, wire 3I, coil 26,- to ground 26, and from ground 31 through wire 36 to the negative side of the source of power 36. The valve winding energizing circuit extends from the positive side of the source of power 36, through tapped resistance IIII, commutator resistance I020 and brush I 03 of rheostat 3I, wire 32,. to the wires 39 and II, and thence cross wire I3, and wire II to the ground I6 and from ground 31 to wire 36 to the negative side, of the source of power 35. Thus, upon operation of the triple valve I2 to connect the reservoir II with the pipe It, the switch plate 25 is brought into engagement with the contacts 26 and 27 to complete the energizing circuit for the coil 29. The intensity of energization of the windings and the \coil depends upon the amount of resistance inserted between the source of power 35 and the wires 32 and 33 by the rheostat 3I. The amount of resistance inserted between the source of power 35 and the wires 32 and 334s proportionalto the speed of the vehicle axle due to the control of the rheostot 3I by the centrifugal rheostat control mechanism, the structure and operation of which will be hereinafter more clearly described. v

The details of the electromagnetic valve device are-illustrated in Figure 2. The inlet valve I3 is provided with a housing having a cap plate I1 rigidly secured to the upper end thereof by 76 tends which is provided, at its upper means of screw bolts 48. The housing 46 is provided at its upper end with a suitable supporting chamber in which is disposed the winding 49 which is suitably insulated from the metallic housing 46 and cap plate 41. The inner side of the cap plate 41 is provided with a projection 41a which is surrounded by one end of the compression spring 50. Thelower end of the compression spring 50 abuts the armature5| which has at its upper end within the lower end of the compression spring 50. A similar projection 5|ais disposed at the bottom end of the armature 5| and extends into the upper end of the compression spring 52 which is in abutment with the armature 5|. The compression spring 52 extends into the upwardly extending cylindrical portion of the cup-shaped spring shoe 53 which is slidable in the housing 46 and which rests upon the diaphragm 54 which is secured between the lower end of the housing 46 and the extension 56 of the casting 51. The housing," is screw-threadedly attached to the extension 56.

The casting 51 which is cylindrical is provided with an extension 58 disposed oppositely and in alignment with the extension 56, and also an ex=- tension 58, which is axially spaced from the extension 56. The cylindrical casting 51 is provided with a wall 60, which divides the cylindrical portion thereof into two chambers, namely, the inlet chamber 6| and the pressure chamber 62. This wall is provided with a horizontal port 63 having a valve seat upon which rests the valve member 64. This valve member 64 is connected by the stem 65 with the piston 66 which reciprocates in the cylinder 61 provided in the extension 58.

The lower end of this cylinder 61 is closed by the cap 68 which is screw-threadedly attached to the extension 58. The cylinder 61 communicates with the pressure chamber 62 through the pas= sage 69 in the top wall 18 of the cylinder 611, which is provided with a central boss in which the stem 65 is slidably supported.

Screw-threadedly secured in the upper portion of the wall 60 is the valve supporting member it end adjacent the diaphragm 54, with a cylindrical chamber it. The lower end of the member 19 is provided with a seat 13 which is adapted to cooperate with the valve member 14 which is secured by the'stem 15 to a nut member 16 which is disposed in the chamber 12 and normally urged upwardly therein by the spring 11 which has the upper end thereof in engagement with the nut member 16 and the lower end thereof in engagement with the lower wall of the chamber 121 A suitable amrture is provided in the member 1| between the chamber 12 and the seat 13 to slidably support the stem 15. A pressure chamber 18 is also provided in the member 1| above the seat '13 and this chamber is connected by the passage 19 to the lower end of the cylinder 61 below the piston 66. Sur roundingthe upper end of the member if i which is provided with the chamber 12, is the auxiliary pressure chamber 80 which is connected by the passage 8| to the pressure chamber 62.

The inlet valve 46 operates as follows: When the resistance inserted in the energizing circuit of the valve 40 is 0! maximum ohmic value, the position of the parts of the valve 40 is shown in Figure 2. Due to the minimum intensity of energization of the winding 49, the downward force applied by the armature 5 to spring 52 is of minimum value. The spring shoe 53 is applied with minimum force to the diaphragm 54 to unseat the a projection 5|a which exthe spring shoe 53 varies gization valve member 14 inlet chamber 6| to pass through the chamber 18 and passage 19 to the lower part of cylinder 61 below the piston 66. The valve member 64 will be unseated and fluid under pressure will pass from the inlet'chamber 6| through port 68 to the pressure chamber 62. This pressure in the pressure chamber 62 will be transmitted through passage 8| to auxiliary pressure chamber and thus applied to the diaphragm 54.

When the pressure in the pressure chamber 62 and the proportional pressure in auxiliary pressure chamber 89 is suflicient to overcome the downward force applied to the spring shoe 53, the diaphragm 54 is thrust upwardly to permit the spring 11 to seat the valve member 14 and shut oil the pressure applied in cylinder 61 below the piston 66. The valve member 64 will then be closed. As the pressure applied downwardly by directly with the intensity of energization oi. the winding 49, the necessary pressure built up in the auxiliary pressure chamber 80 to cause seating of the valve member 64 will vary directly with the intensity of energization of the winding 49. The intensity of energization of the winding 49 will, therefore, control the fluid pressure which passes from the inlet chamber 6| to the pressure chamber 62. When the intensity of energization of the winding 49 is increased by reduction of resistance between the source of power 35 and the wire 33, the pressure necessary to be built up in the pressure chamber 62 to close valve member 64 will be proportionally reduced. The reason for maximum enerof the solenoid 49 at slow speed and subsequent creased is to overcome any danger of cutting oii the air supply to cylinder |1 should the solenoid energizing circuits be damaged.

The release valve 42 is provided with a housing 83 which is screw-threadedly attached to the extension 59. The upper end of the housing 831s closed by a cap plate 84 similar to the cap plate 4'5 and having a central projection 84a similar to the projection 41a. The cap plate 84 is secured to the housing 83 by the bolts 85. The upper portion of the housing 83 is provided with a chamber which contains the winding 86 which is similar to the winding 49 and which is insulated winding 39 is insulated from the housing 46. Disweakening thereof as the speed is inand permit pressure from the posed in the housing 83 and cooperating with the winding 86 is the amature to the armature tit and which is biased downwai'dly by the compression spring 88 similar to the compression spring 58, which has its upper end surrounding the projection 84a and its lower end surrounding the projection 81a on the arms? ture ill.

"Below the armature till and having its upper end in engagement with the armature 81 is the compression spring 89 which has its lower end in engagement with a suitable groove in the thrust platetd. The thrust plate 90'is secured by means of the nut St to the reduced upper end of the valve stem 96 which has the valve member 92 integral with the lower end thereof. The housing83 is provided with a horizontal lower wall 9t having a central boss provided with a suitable aperture for slidably supporting the valve stem 93. The lower wall 94 is also provided with a passage 95 which leads from the lower side thereof radially outwardly to the atmosphere. The extension 59 is provided with a. lower reduced bore 96 having a valve seat 91 81 which is similar Gil at its upper end for cooperation with the valve member l2.

Above the valve seat II, the extension ll is provided with an enlarged bore whichcooperates withthewallllofthehousinglltoformthe exhaust chamber ll having constant communication, through the e ll, with the atmosphere. The springsv ll and ll and the armature ll apply downward force to the thrust plate j! by rheostat ll. The pressure chamber l2 communicates directly with the wheel brake cylinder II and, therefore, the pressure in the chamber ll and in the cylinder J1 is equal. When the winding ll is de-energized. and when the pressure in the chamber l2 and cylinder i1 is sufllcient to unseat the valve member l2, fluid escapes through exhaust chamber ll and passage ll to the atmosphere.

As will hereinafter more clearly appear, the amount of resistance inserted in the energizing circuits by the rheostat l4 varies directly with' the speed of the vehicle. If, while the vehicle is traveling at high speed, pressureis reduced in" the brake pipe I to cause operation of the triple valve I! to connect the reservoir II with the pipe ll, the brake coil energizing circuit is completed by the pressure responsive switch ll to energies the track brake coil at an intensity which is governed by the speed controlling governor. As the vehicle decelerates, the speed responsive rheostat l4 progressively cuts out resistancein the valve energizing circuits to strengthen the solenoids of the valve device ll. The strengthening of the intensity of energization of the winding ll reduces the downward force applied to the valve member l2 and, where the pressure in the chamber H is sufliclent, the valve member ll will be unseatedand the pressure exhausted until the pressure in the pressure chamber l! and the brake cylinder i1 is reduced to a value proportional to the intensity of energization of the winding-ll. The speed of the vehicle at the time of initial application determines the intensity of energiaation of'the winding ll of the valve member ll and, therefore, determines the amount of fluid pressure initially admitted through the valve ll to the pressure chamber l2 and the brake cylinder II which is indirect communication therewith.

. The rheostat 34 comprises the casing'll hava ing rotatably mounted therein the rotor shaft ill. The rotor shaft Ill has rigidly secured thereto the rheostat rotor Ill, to which is rigidly secured the armature ill. The rheostat rotor III is provided'with a plurality of contact plates Illa suitably insulated from one another and each adapted to have progressively connected thereto a tap of a tapped resistance element Ill.

'The end tap of the raistance ekment ill is connected by wire lllb to the armature resistance lllc which has each of its respective taps-connected to an armature plate-Illa of the armature ill. I

Secured in known manner in the casing ll is L control Ill succesively contacts various of the plates g Illa of the armature Ill. Various resistance values are thereby inserted between the wire 32 andthesourceofpowerllinordertoweaken or strengthen the valve energizing circuits as described above. The armature 'lll is soarraugedwithrespecttothebrushlll that, whenthe speed of the vehicle is zero, the mini- 'mum resistance valueis inserted between the wire ll and the source of power ll Upon increase of the vehicle speed, the shaft in is caused to rotate by operation of the governor mechanism to revolve the shaft Ill in the directionindicatedbythearrowinl'lgureitnprogressively increase the resistance value inserted between wire I! and source of power ll, whereby to so control the valve energizing circuits. that the intensity of energization of the valves ll and 42 is proportional to the speed of the vehicle.

tUpon rotation of the shaft Ill. as described above, the proportion of the resistance element Ill inserted between source ofpower 35 and contactor bar ilib is decreased and the intensity of energlzation of the brake coil ll is thereby varied dlreetlywith thespeedofthe vehicle. t

For the purpose'of balancing the circuits of thevarlousvehiclesinatraimaiflxed Ill is inserted between the collector brushes Ill and thesource of power ll. The value of this resistance may be changed for the purpose of balancing the respective circuits and for changing the operating characteristics of the respective The arrangement of the brush Ill, coutactor bar Illb, the plates Illa anldresistance ills of the armature Ill and the co ector brushes Illa are tically illustrated in Figure 4, which also shows the manner in which the resistance element ill is insertedin series-with the source of power ll between the source of power and the rheostatll.

The construction of the speed responsive governor for controlling the rheostat II is shown inl'igurelandcomprisesthemaincasting Ill having the base casting ill rigidly secured thereto by means of bolts Ill, which extend through abutting flanges Each oi the castas ill and ill is Provided with oppositely disposedsani-circuiarbearingmembers at oppositesideswhichareadaptedtoformanannular bearing for surrounding the axle l which is cssting Ill is provided with a bowlr of a railway vehicle.

ably pivotally attached to the truck or frame Suitably secured to the top of the governor housing III is the cap plate II4 which is provided with central thrust bearing means for supporting the rotor shaft II5 which is provided at its lower end with a pinion H6 which is rigidly secured thereto. The pinion H5 is adapted to mesh with a gear l II, which is a split gear comprising'halves clampingly secured to the axle I I by means of bolts or other suitable means. By means of this connection, rotation of the axle I I0 is translated into rotation of the governor shaft I I in either direction at a speed proportional to the speed of rotation of the axle Wand, necessarily, to the speed of the vehicle when perfect traction exists between wheels and track rails. Rotor shaft I00 is provided with a gear I I8 which is rigidly secured thereto and which engages a rack I on the sleeve II9 which is axially slid- I able on the shaft II5.

At its upper end, the sleeve 9' is provided with an annular flange which is rigidly secured within the thrust collar I2I which comprises complementary members bolted or otherwise rigidly secured together, the top member of which is provided with oppositely disposed ears I22, each having the lower end of a link I23 pivotally attached thereto. The upper end of each link I23 is pivotally secured to a. weight lever I24. The weight levers I24 are provided with weight members I25 I26 on the shaft I I5. By means of this structure, the thrust collar I2I and the sleeve I I9 will move upwardly, upon rotation of the axle IIO, a distance proportional to the speed of the axle H0. The rotor shaft I00 will be rotated through an are proportional to the speed of the axle I i0 because of the engagement of the gear I I8 with the rack I20 on the sleeve I I9. Therefore, by means of this structure, the resistances inserted by the rheostat 34 between the source of power 35' and the wires 32 and 33 are proportional to the speed of the vehicle.

Due to the fact that, upon application of .the brakes of a railway vehicle, the weight will be distributed on the axles of the vehicle in such manner that the weight on the forward axles is increased and the weight on the rear axles is decreased, it is preferred that the rheostat 34 and the controlling governor mechanism be mounted on the rearmost axle of the car. The advantage of this disposition of the rheostat and controlling governor is that the governor mechanism is made responsive to the speed of the rearmost axle, the wheels IIOa of which will be most likely to slide on therail due to loss of traction between the wheels and the'rails. The rearmost wheel brakes will, therefore, be most likely to be locked and the speed of the rearmost axle be the most likely to be brought first to zero. Therefore, upon the locking of the brakes on the wheels of the rear axle, the rheostat 34 will insert the correct resistance between the wires 32 and 33 and the 35, whereby to cause the strengthening of the energizing circuits and necessarily decrease the air pressure in the air brake cylinder I1 by stopping the fiow of fluid pressure through valve 40 and exhausting suificient fluid pressure to permit the wheels to unlock and begin turning.

While Figure 1 illustrates the application of the principles of our invention to a vehicle equipped with conventional track brakes which at the outer ends and have theirinner and upper ends pivotally secured to ears are applied solely by energization of the coil 29 thereof, it is, of course, to be understood that our invention is susceptible of application to vehicles unequipped with track brakes, in which case the wires 3| and 33, the pressure responsive switch 20, the pipe I9 and the track brakes will be omitted.

Furthermore, the control means may be con' nected to the track brake circuit alone, the electromagnetic valve device I6 and wire 32 being omitted by connecting the pipe I5 directly to the cylinder II, as is conventional practice.

It is also contemplated by us that the principles of our invention may be applied to a vehicle equipped with track brakes which are applied by energizatiomof a solenoid connected in the track brake energizing circuit, as illustrated in Figure 6. A form of this type of brake is illus trated in United States Letters Patent No. 1,724,266 granted August 13, 1929, to T. Elliott.

As shown in Figure 6, the solenoid I2I is connected in the energizing circuit of the coil 29 and is energized simultaneously therewith and the intensity of energization of the solenoid I21 is proportional to the intensity of energization of the coil 29. The brake shoe is supported by springs I28 at such distance from the rail that the rail is spaced from the magnetic field thereof. Cooperating with the solenoid I2'I is the armature I29 which is pivotally attached to the intermediate portion of the lever I30 which has one end suitably pivotally supported on the railway vehicle and the other end thereof provided with a projection which engages the top of the track brake shoe 30. Upon energization of the solenoid I21, the lever I30 is drawn downwardly to move the shoe 30 downwardly against the upward force of the springs I28 so that the rail will be disposed within the magnetic field of the energized shoe. 'This causes application of the shoe 30 to the rail. The necessary modification of the circuit and the structure shown in'Figure l is illustrated in Figure 6.

It is further contemplated that the principles of this invention may be applied to railway vehicles equipped with track brakes which are positioned, by fiuid pressure, sufilciently close to the rail to permit energization of the shoe 30 to cause application thereof to the rail. Such structure is illustrated in Figure 5 and comprises the air engine l3i which has a cylinder I32,'ln which is slidably disposed a piston I33 which is urged upwardly by the compression spring'I34. The piston I33 is connected by the stem I35 to the top of the track brake shoe 30. The upper end of the cylinder i32 is connectedby pipe I36 to the pressure chamber 62 oi the electromagnetic valve device it. The track brake shoe 30 is thus normally supported by the spring I34 at substantial distance from the rail. When, however, fluid pressure builds up in the pressure chamber 62, this fluid pressure is transmitted through pipe i3i5 to the upper end of the cylinder I32 above the piston 1133. When sufiicient fluid pressure is built up above the piston I33, the stem I35 will be thrust downwardly at a rate proportional to the pressure in the cylinder I32, whereby to position the brake shoe sufficiently closely adjacent the rail to place the rail within the magnetic field oi the energized track brake shoe.

The speed of application is, therefore, proportional to the pressure supplied to the cylinder I32 from the pressure chamber 62 of the electromagnetic valve device I6. The speed of application {or a given fluid pressure may be varied by intensity of track brake application varying the strength of the compression spring I34. The time required for application of the shoe to the rail may be varied by varying the length of the stem I fluid engine I3I from the rail. application of the shoe to the rail will also be proportional to the fluid pressure in the cylinder I32, because the upward force or the spring acts in opposition to the downward iorce exerted by the fluid pressure and weight of the brake shoe.

Operation In the operation of the above-described mechanism, the pressure in the brake pipe I is reduced in known manner and the triple valve I2 operates to connect the pipe I3 with the pipe I5. whereby to transmit the fluid pressure from the reservoir I4 to the pressure responsive switch 20. Upon operation of the pressure responsive switch 29, the switch plate 29 engages the contacts 23 and 21 to complete the energizing circuit of the track brake coil 29. The intensity 0! energization of the windings of the valves 43 and 42 and of the coil 29 of the track brake shoe will be proportional to the speed of the vehicle at the time the application is initiated because the amount of resistance between the source oi power 39 and the wire 33 is always proportional to the speed of the axle III). The pressure admitted to the pressure chamber 62 will likewise be proportional to the speed of the axle Ill.

If the vehicle is traveling at high speeds, relatively little resistance will be'inserted by the rheostat 34 between the source of power 39 and wire 33 and, therefore, the intensity of energization of the brake coil 29 will be substantially great, likewise the amount of resistance in circuit with wire 32 to the valve device It will be high and the fluid pressure supplied to the cylinder IT will, likewise, be substantially great. Therefore, as energization oi the coil 29 of the track brake shoe takes place simultaneously with operation of switch 29, simultaneous application of the wheel brakes and the track brake will be produced.

As the speed of the vehicle is reduced, added resistance is progressively inserted between thesource of power 35 and wire 33 by the rheostat 34. This decreases the intensity of energization of the track brake coil and likewise, as the speed is'reduced, resistance is progressively cut out between the source of power 39 and wire 32 by the rheostat 34 to increase the intensity oi energization oi the valve windings 49 and 86, the pressure in the pressure chamber 92 of the magnetic valve device'IO is reduced to reduce the pressure of wheel brake application while the is simulby reduccoil 29 01' taneously and proportionally reduced tion 01' intensity of energization of the the track brake shoe 39.

Where the track brake is omitted, the operation is similar, save that the only function performed by the rheostat 34 is to control the intensity of energization oi the windings of valves 49 and 42.

Where the type oi brake utilized is that illustratcd in Figure 6, the operation is as described above, the only difference being that the solenoid I21 is energized to an intensity proportional to the intensity of energization oi the coil 29, whereby downward force applied by the lever I3I to the brake shoe 39 is likewise controlled. I

Where the structure is as illustrated in F gl 't or the distance of the The intensity of the fluid pressure supplied to the cylinder I32 sure in the pressure chamber 92 of the magnetic valve device It and, as this pressure is controlled, as described above, by controlling the energization of the windings of valves 49 and 42, the fluid. pressure above the piston I33 in the cylinder I32 is likewise controlled. As the speed of the vehicle decreases, added resistance is progressively inserted by the rheostat 34 in the respective energizing circuits whereby to reduce the intensity of energization of valves 40 and 42 along with the coil 29 of the track brake. As the intensity oienergization of the windings 01' valves 49 and 42 is decreased, the pressure in the pressure chamber 62 of the valve device II is progressively reduced, whereby to progressively reduce the fluid pressure in the wheel brake cylinder I1; and. pressure in the air engine I3I. when the pressure in the air engine I3I is thus reduced to a point where the force of the spring I34 is suiiicient to overcome the force of the coil 29, the intensity of which energization has as explained above, the track.brake will be released from .the rail; and likewise, when the pressure in cylinder I1 is sufllciently reduced, the wheel brakes will be released.

It will thus be seen that the intensity oi initial application is proportional to the speed of the vehicle and that the intensity of both wheel and track brake application is progressively reduced as the speed of the vehicle decreases to zero and as the co-eillcient oi braking'iriction increases. The ultimate brahng efllciency is thus in the case oi Figure 5, also the.

been reduced,

achieved automatically without reliance upon human discretion, the controlling factor of the above operation being the speed of rotation of the rearmost axle which, due to the above debrakes, in addiporting rails or to decrease slippage between the wheels and the supporting track rails.

It is, of course, to be understood that, by suitable adjustment oi'various oi' the above-described mechanisms, the operating characteristics may be widely varied.

It is further to be understood that the principles of this invention may be applied to vehicles of various constructions having braki element is thus systems of various types other than that here illustrated and described above.

The term intensity of brake application is herein used t0 designate force of brake application.

described structure is merely illustrative of the manner in which the principles of our invention may be utilized and that we desire to comprehend within our invention such modifications as come within the scope of the claims and the invention.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is: i

1. In brake control mechanism for a rail veluc e vi g wheel brakes and track brakes, com- It is likewiseto be understood that the above-- mon means for causing application of said wheel brakes and said track brakes, and means responsive to the speed of the vehicle for constantly maintaining the intensity of application of said brakes proportional to the speed of said vehicle during brake application, said last-named means including a biasing rheostat and acentriiuzal governor device operatively connected to an axle of the vehicle.

2. In brake control mechanism for a rail vehicle' having wheel brakes and track brakes, comtaining the intensity of initial application of said I brakes proportional to vehicle speed comprising electromagnetic valve means for controlling the admission of fluid pressure to' said cylinder, a common circuit for energizing said valve means and said track brake, and means including a rheostat in said circuit responsive to the speed of a vehicle axle for maintaining the intensity of energization of said valve means and said track brake proportional to the speed ofthe vehicle.

4. In brake control mechanism for a railway vehicle having wheel brakes, means including a fluid cylinder for applying said wheel brakes, and an electromagnetic track brake adapted to be applied by energization thereof; means for constantly maintainingthe intensity 0! application of said brakes proportional to vehicle speed dur- -mon circuit said last-named.

.tional to vehicle said vehicle, said last-named means including a ing deceleration of said vehicle comprising electromagnetic valve means for controlling the admission of fluid pressure to said cylinder, a comior energizing said valve means and said track brake, and means including a rheostat in said circuit and a centrifugal governor device connected to a vehicle axle for controlling said rheostat whereby to maintain the intensity of enersization of said valve means and said track brake proportional to the speed of the vehicle during deceleration.

5. In brake control means axles,- wheel brakes, and track brakes; common means for applying said wheel brakes and said track brakes, and common means for determining the intensity of initial application of said wheel and track brakes, said last-named means including an electromagnetic valve device for controlling the intensity or application of said wheel brakes, a common circuit for energizing said valve device and said track brake, a rheostat in said circuit, and a centrifugal governor mechanism operatively amociated with one of said axles and with said rheostat.

6. In wheel brake control means for a vehicle having axles, wheel brakes, and track brakes; common means for applying said wheel brakes and said track brakes, common means for determining theintensity of initial application of said wheel and track brakes and for maintainingthe intensity of, application of said brakes proporspeed during deceleration oi.

common circuit for controllingthe intensity of application of said brakes, a rheostat in said circuit, and centrifugal governor means operatively connected to one of the vehicle rheostat.

TI-IEODORE H. SCHOE IPF.

DAVID M. RITCHIE.

for a vehicle having axles and to said 

